Much effort has been spent on developing techniques that are intended to reproduce a sound recording with improved quality, so that it sounds as natural as in the original recording environment. The approach is to create around the listener a sound field whose spatial distribution more closely approximates that of the original recording environment. Early experiments in this field have revealed for example that playing a music signal through a loudspeaker in front of a listener and a slightly delayed version of the same signal through a loudspeaker that is behind the listener gives the listener the impression that he is in a large room and music is being played in front of him. The arrangement may be improved by adding a further loudspeaker to the left of the listener and another to his right, and feeding the same signal to these side speakers with a delay that is different than the one between the front and rear loudspeakers.
A stereophonic recording captures a sound environment by simultaneously recording from at least two microphones that have been strategically placed relative to the sound sources. During playback of these (at least two) input audio channels through respective loudspeakers, the listener is able to (using perceived, small differences in timing and sound level) derive roughly the positions of the sound sources, thereby enjoying a sense of space. In one approach, a microphone arrangement may be selected that produces two signals, namely a mid signal that contains the central information, and a side signal that starts at essentially zero for a centrally located sound source and then increases with angular deviation (thus picking up the “side” information.) Playback of such mid and side signals may be through respective loudspeaker cabinets that are adjoining and oriented perpendicular to each other, and these could have sufficient directivity to in essence duplicate the pickup by the microphone arrangement.
Loudspeaker arrays such as line arrays have been used for large venues such as outdoors music festivals, to produce spatially selective sound (beams) that are directed at the audience. Line arrays have also been used in closed, large spaces such as houses of worship, sports arenas, and malls.